Composition and method for reducing noise and/or fouling in a liquid cooling system

ABSTRACT

A composition for use in reducing noise in a liquid-cooling system of an engine, eg an automotive engine, comprising an organo-polymeric microfibril material insoluble in the cooling liquid of the liquid-cooling system. Preferably the microfibril material is contained in a carrier, which maybe in the form of a liquid, a gel or a compressed tablet soluble or dispersible in the cooling liquid.

DESCRIPTION OF INVENTION

This invention relates to a composition for use in reducing noise and/orfouling in a liquid cooling system of an engine, and a method ofreducing noise and/or fouling in such a liquid cooling system.

It is known that noise is produced as a result of vortexing cavitation,and eddying when liquid flows in pipes, ducts, and hollow castings.

The methods currently used to reduce noise produced by liquid flowing inclosed systems specifically the cooling system of a heat engine, has todate been concentrated on macro-mechanical aspects, i.e. by varying thepump specification or surrounding the sound source in sound absorbingmaterials, or increasing the thickness of the liquid container. Othermethods have been to reduce the cooling system volume to a minimum or topolish the internal surfaces of the coolant conducting pipes whosenormal bend, constrictions, expansions, and roughness promote thevortexing cavitation, and eddying that produces vibrations and noise.

All these methods have limited application, and fail to resolve theprimary causes of the noise, i.e. cavitation. vortexing, and eddyingproduced as the liquid circulates.

An object of the present invention is to provide a composition and amethod of reducing (the primary causes of noise at a “micro-mechanical”level resulting in reduced cavitation, vortexing, and eddying, andtherefore noise.

A first aspect of the invention provides a composition for use inreducing noise fouling in a liquid cooling system of an enginecomprising an organo-polymeric microfibril material insoluble in thecooling liquid of the liquid cooling system, the microfibrils having anaspect ratio (length to diameter) in the range 10 to 5000.

A second aspect of the invention provides a method of reducing noiseand/or fouling, in a liquid cooling system of an engine comprisingadding the composition according, to the first aspect of the inventionto a liquid cooling system of an engine.

The microfibril material when introduced into the liquid cooling systemreduces cavitation, vortexing, eddying, and therefore noise. In additionit reduces the fouling, if any, of the internal surfaces of the coolingsystem.

Preferably the aspect ratio is in the range 10 to 3000. Excessive aspectratio would lead to entanglement of individual microfibrils, and henceprecipitation in the flowing, liquid.

Preferably, the organo-polymeric microfibril material is a solid organicpolymer in the form of microfibrils having an average diameter in therange of 1 nm-15 μm, an average length in the range of 100 nm-3 mm.Polymeric materials to be processed into microfibrils should beinsoluble but highly dispersible in a given coding liquid. There may beused for example polyethylene, polyproplyene, polystyrene, polyvinylchloride, polyvinylidene chloride, polytetrafluoroethylene, polyethyleneterephthalate, polymethylmethacrylate nylon, polycarbonate, andcopolymers or blends thereof.

Polymeric compounds known for their heat resistance may be used whichinclude para-amides, aromatic polyamides, aromatic polyethers,polyetheretherketones, aromatic polyesters, aromatic polyimides, andpolybenzoimidazoles.

Polymeric materials that have been found particularly preferable arethose which are capable Of forming a liquid crystal. Specific examplesinclude aramide fibres such as poly-p-phenylene terephthalamide wet spunfrom sulfuric acid liquid crystal solutions, and polybenzobisthiazolewet spun from polyphosphoric acid liquid crystal solution.

By “microfibril” is meant short lengths of fibre. The microfibrils arenot microfibrillated.

By “highly dispersible” is meant the state of the polymeric microfibrilswhich can be seen to form a uniform suspension after being vigorouslymixed for a period of time.

The choice of polymeric microfibril material will depend upon theparticular kind of cooling liquid in which the material is used;clearly, the material should not react chemically with the coolingliquid of the liquid cooling system, nor with the carrier liquid.Furthermore, the polymeric microfibril material should not be readilydegradable, but should have a reasonable life in the cooling liquid.

What is meant by the microfibrils being “insoluble” in a liquid may bedetermined by an experiment in which 1 weight percent of polymericmicrofibrils is added to the liquid, and stirred vigorously for fivehours at a working temperature, followed by filtration, and dryingwhereupon the material is measured for weight reduction. If thisreduction is less than 10 weight parent of the original weight then themicrofibril material is regarded as insoluble.

There is no restriction placed on how to make the polymeric microfibrilmaterial.

In order to improve the dispersibility of the microfibril material inthe cooling liquid, and to enhance the stability of the resultingsuspension, the material may be treated with a suitable surfactant, orchemically modified, or physically treated.

A suitable surfactant is modified alcohol “Ethylan CPG660” or “Monolan8000/E80” of Ackros Chemicals Limited.

The cooling liquid of the liquid cooling system may be aqueous ornon-aqueous, e.g. hydrofluroether, water, oils, a liquid hydrocarbon orany other suitable liquid coolant.

In order to reduce the risk of dust health hazard, the said material ispreferably contained in a carrier, The carrier may be, e.g. a liquid, agel or a compressed tablet soluble a dispersible in the said coolingliquid.

The carrier is preferably completely soluble in the cooling liquid. Whenthe carrier is a liquid or a gel it should prevent settling of thepolymeric microfibril material during storage, and promote accuratedosing during packaging, or in production line application requiringportioning of bulk quantities. Such a carrier could be magnesiumaluminium silicate in suspension, propylene glycol, cellulose solutionor any other suitable compound.

The method of the invention finds effective application where liquidsare used in closed cooling systems particularly where noise pollution orfouling are negative factors of the system, as with automotive cooling,systems, and more generally where any heat engine with a liquid cooledsystem is employed.

The invention will now be described with reference to the followingexamples:

EXAMPLE 1

A suitable suspension was prepared by blending a water glycol mixture(approximately 33% by weight of glycol), and a surfactant (modifiedalcohol ethoxylate at 6 ppm with polymeric microfibrils of Nylon-6 ofsize 10 nm by 1 μm, i.e. an aspect ratio of 100, at 50 ppm. The solutionwas subjected to 10,000 cycles in an automotive cooling system

As compared with the use of a water glycol mixture on its own, theaddition of the polymeric microfibril material produced a substantialnoise reduction. However, the noise reduction decreased proportionallywith increasing cycle number throughout the test; sonic degradation ofthe suspension was observed.

In addition, as compared with a water glycol mixture on its own, theaddition of the polymeric microfibril material produced a measurablereduction in surface fouling within the cooling system.

EXAMPLE 2

A stable suspension was prepared by blending a water glycol mixture anda surfactant at 6 ppm as in Example 1 with polymeric microfibrils ofaramide, i.e. poly-p-phenylene terephthalamide (e.g. Du Pont's KEVLAR®)of size 12 μm by 250 μm, i.e., an aspect ratio of 20.9, at 100 ppm. Thesolution was subjected to 10,000 cycles in a closed system.

As compared with the use of a water glycol mixture on its own, thepolymeric microfibril material produced a consistent reduction in noisethroughout the test and no degradation of the suspension was observed.The noise reduction observed was greater than for Example 1.

In addition, as compared with a water glycol mixture oil its own, theaddition of the polymeric microfibril material produced a measurablereduction in surface fouling within the cooling system.

EXAMPLE 3

A stable suspension was prepared by blending a water glycol mixture, anda surfactant at 6 ppm as in Example 1 with polymeric microfibrils ofpoly-p-phenylene terephthalamide of size 5 μm by 250 μm, i.e. an aspectratio of 50, at 400 ppm. The solution was subjected to 10,000 cycles ina closed system.

As compared with the use of a water glycol mixture on its own, thepolymeric microfibril material produced a consistent reduction in noisethroughout the test, and no degradation of the suspension was observed.The noise reduction observed was greater than for Example 2.

EXAMPLE 4

A stable suspension was prepared. by blending a water glycol mixture anda surfactant at 6 ppm as in Example 1 with polymeric microfibrils ofpoly-p-phenylene terephthalamide of size 50 nm by 250 μm, i.e. an aspectratio of 5000, at 100 ppm. The solution was subjected to 10,000 cyclesin a closed system.

As compared with the use of a water glycol mixture on its own, thepolymeric microfibril material produced a consistent reduction in noisethroughout the test and no degradation of the suspension was observed.The noise reduction observed was even greater than for Example 3.

The noise reduction observed was typically in the range 8 to 15 dB atfrequencies in the range 3 to 10 KHz.

The anti-fouling observed, which is difficult to quantify, was that ofthe internal surfaces of the cooling system becoming generally cleanerand on most occasions in removal or apparent calcifications.

The anti-fouling observed which is difficult to quantify, was that ofthe internal surfaces of the cooling system becoming generally cleanerand on most occasions the removal of apparent calcifications.

In order to reduce the noise and fouling, if any, in a vehicle engineliquid cooling system, the composition is added to the expansion tank ofthe vehicle radiator, or directly into the radiator. If the carrier is aliquid the composition may be contained in a bottle. The bottle would beshaken before the contents are added in the cooling system. Noisereduction is achieved once the composition has been completely dispersedin the cooling system, and this occurs rapidly once the engine isrunning. The anti-fouling effect is observed over a period of timeduring which the engine has been running. The composition may be removedby draining and flushing the cooling system.

It should be understood that the term microfibril is intended to meanonly short lengths or fibres. The microfibrils are nor microfibrillatedas this would degrade the performance of the composition as themicrofibrils would tend to become entangled and thus flock or clumptogether and sediment out rather than remain in suspension. It is alsopreferred that the microfibrils should be formed of flexible rather thanbrittle material, as in the latter case the microfibrils breakdown overtime and the performance of the composition is again degraded.

The features disclosed in the foregoing description the following claimsor the accompanying drawings expressed in their specific forms or interms of a means for performing the disclosed function, or a method orprocess for attaining the disclosed result, or a (lass or group ofsubstances or compositions, as appropriate, may, separately, or in anycombination of such features, be utilised for realising the invention indiverse forms thereof.

What is claimed is:
 1. A composition for use in reducing noise and/orfouling in a liquid cooling system of an engine comprising anorgano-polymeric microfibril material insoluble in the cooling liquid ofthe liquid cooling system, the microfibrils having, an aspect ratio(length to diameter) in the range 10 to
 5000. 2. A composition accordingto claim 1 wherein the aspect ratio of the microfibrils is in the range10 to
 3000. 3. A composition as claimed in claim 1 or 2, wherein thesaid material is contained in a carrier.
 4. A composition as claimed inclaim 3, wherein the carrier is a liquid, the said material beinginsoluble and dispersible in the carrier liquid.
 5. A composition asclaimed in claim 3, wherein he carrier is a gel soluble in the saidcooling liquid, the said material being insoluble and dispersible in thegel.
 6. A composition as claimed in claim 3, wherein the carrier is inthe form of a compressed tablet soluble or dispersible in the saidcooling liquid.
 7. A composition as claimed in claim 4, wherein thecarrier liquid is a glycol, a magnesium aluminium silicate in suspensionan alcohol, or a hydroxybenzoate.
 8. A composition as claimed in claim1, wherein the said material has an average diameter from 1 nm-15 μm, anaverage length from 100 nm-3 mm.
 9. A composition as claimed in claim 1,wherein the said material is selected from para-amides, aromaticpolyamides, aromatic polyethers, polyetheretherketones, aromaticpolyesters, aromatic polyimides, polybenzoimidazoles, polyethylene,polypropylene, polystyrene, polyvinyl chloride, polyvinylidene chloride,polytetrafluoroethylene, polyethylene terephthalate,polymethylmethacrylate, nylon, polycarbonate, and copolymers or mixturesthereof.
 10. A composition as claimed in claim 9, wherein, the saidmaterial is capable of forming a liquid crystal.
 11. A composition asclaimed in claim 10, wherein the compound is poly-p-phenyleneterephthalamide or polybenzobisthiazole.
 12. A composition as claimed inclaim 1, wherein the carrier includes a surfactant to facilitatestability of the said material in the cooling liquid of the liquidcooling system.
 13. A method of reducing noise and/or fouling in aliquid cooling system of an engine by adding to the cooling liquid acomposition as claimed in claim
 1. 14. A method as claimed in claim 13,wherein the amount of composition added is 0.1 ppm to 5 percent byweight of the cooling liquid.
 15. A method as claimed in claim 13 or 15,wherein the composition is added to the cooling liquid of in automotivecooling system.
 16. A composition as claimed in claim 3, wherein thesaid material has an average diameter from 1 nm-15 μ, an average lengthfrom 100 nm-3 mm.
 17. A composition as claimed in claim 4, wherein thesaid material has an average diameter from 1 nm-15 μ, an average lengthfrom 100 nm-3 mm.
 18. A composition as claimed in claim 3, wherein thesaid material is selected from para-amides, aromatic polyamides,aromatic polyethers, polyetheretherketones, aromatic polyesters,aromatic polyimides, polybenzoimidazoles, polyethylene, polypropylene,polystyrene, polyvinyl chloride, polyvinylidene chloride,polytetrafluoroethylene, polyethylene terephthalate,polymethylmethacrylate, nylon, polycarbonate, and copolymers andmixtures thereof.
 19. A Composition as claimed in claim 4, wherein thesaid material is selected from para-amides, aromatic polyamides,aromatic polyethers, polyetheretherketones, aromatic polyesters,aromatic polyimides, polybenzoimidazoles, polyethylene, polypropylene,polystyrene, polyvinyl chloride, polyvinylidene chloride,polytetrafluoroethylene, polyethylene terephthalate,polymethylmethacrylate, nylon, polycarbonate, and copolymers andmixtures thereof.
 20. A composition as claimed in claim 3, wherein thecarrier includes a surfactant to facilitate stability of the saidmaterial in the cooling liquid of the liquid cooling system.
 21. Acomposition as claimed in claim 4, wherein the carrier includes asurfactant to facilitate stability of the said material in the coolingliquid of the liquid cooling system.
 22. A method of reducing noiseand/or fouling in a liquid cooling system of an engine by adding to thecooling liquid a composition as claimed in claim
 3. 23. A method ofreducing noise and/or fouling in a liquid cooling system of an engine byadding to the cooling liquid a composition as claimed in claim 4.